This is a prospective, observational, registration and follow-up study of women exposed to Betaseron® at the time of conception (i.e., any time from the first day of the last menstrual period) and/or during pregnancy. The Betaseron® Pregnancy Registry is designed to determine whether there is an increased risk or a pattern of birth defects in the offspring of women exposed to Betaseron® at conception and during pregnancy compared to rates from women in the general US population. Secondarily, the Registry will examine rates of spontaneous abortions and other negative pregnancy outcomes in this population. This study will be conducted in the United States (US). The Betaseron® Pregnancy Registry is sponsored by Bayer HealthCare Pharmaceuticals and will be managed by Kendle International, Inc. Late Phase Registries & Epidemiology (Kendle). The scientific conduct and analysis of the Registry will be overseen by an Independent Data Safety Monitoring Board (IDSMB) consisting of external specialists in teratology, epidemiology, maternal and fetal medicine, and neurology (external member details available upon request).